1. Field of the Invention
The present invention relates to an inkjet printing system which comprises a vacuum chamber underneath a printing table that creates multiple vacuum zones on the top of the printing table by a movable vacuum divider.
2. Description of the Related Art
To create multiple variable vacuum zones on the top of a printing table to hold several pieces of substrate, several methods and systems are known in the state of the art.
An example of such a system for either typewriters or printers is disclosed in U.S. Pat. No. 4,792,249 (CREATIVE ASSOCIATES LIMITED PA) wherein the vacuum chamber is sectored so that the reduced air pressure is applied only in the region which communicates with the paper to be printed by consecutive sectoring walls, as movable vacuum dividers, which are slidable in the vacuum chamber.
Another example of such a system for an image printing device such as an inkjet printer is disclosed in US 2010/0213666 (XEROX CORPORATION) wherein a vacuum chamber is located underneath a porous conveying belt that that varies the vacuum zones in size and position on the porous conveying belt and wherein a movable wall, as movable vacuum divider, is disclosed to adjust the vacuum zones based on the width of the substrate.
DE 102010049258 (WEMHOENER SURFACE GMBH) discloses also a system for a digital printer wherein a vacuum chamber is used with movable partitions that can be adjusted according the width of workpieces that need to be printed by movable vacuum dividers.
In a production environment while using an inkjet printing system, that is capable of creating vacuum zones, contaminations such as paper dust, substrate fibers, ink, ink residues and/or ink debris such as cured ink, contaminate the inner surface of the air channels in the porous printing table and the inner surface of the set of apertures in the bottom surface of the porous printing table, the inner surface of the vacuum chamber and thus also a movable vacuum divider inside the vacuum chamber. These contaminations need to be cleanable in the vacuum chamber itself without creating vacuum leakages else uncontrolled movement of the movable vacuum divider may occur due to obstacles of the contaminations.
It is besides not uncommon that while changing the inkjet printheads in the inkjet printing systems results in a loss of ink on the printing table or that an inkjet printhead is blocked and results in an overfill and a loss of ink on the printing table.
An approach to eliminate this problem is by periodically removing the printing table from the vacuum chamber and if necessary the wrapped conveying belt around the printing table. However this approach results in a significant downtime for the print system, as printing must be halted in order to remove the printing table from the inkjet print device.
An example of a cleaning system in a printing table is disclosed at US 2010/0271425 (XEROX CORPORATION) wherein the vacuum chamber may be configured a vacuum pressure and vacuum exhaust to clean clogged holes in the conveying belt.
There is still a need to provide an inkjet printing system that avoids contamination such as paper dust, substrate fibers, ink, ink residues and/or ink debris such as cured ink in the vacuum chamber to prevent the bad working of a movable vacuum detector in the vacuum chamber and to prevent vacuum leakages.